What feature makes a face attractive? Is it the average proportions
of that face? We examined this popular theory ("averageness hypothesis")
by conducting an experiment: We asked subjects to rate the attractiveness
of all original faces and composites, which were calculated from 2, 4,
8, 16, 32, or 64 original faces. The results are: The attractiveness ratings
of the transformed faces depend on the number of original faces that have
been used to create them. The more original images were used to create
the composite, the more attractive it was rated. (r = 0.57 ** for
female faces, r = 0.64 ** for male faces). On the one hand this result
tends to support the averageness hypothesis put forward by Langlois &
Roggman (1990), on the other hand we could clearly show: The ratings of
the morphed faces also depend on the attractiveness of the underlying original
faces (r = 0.75 ** for female faces, r = 0.68 ** for male faces).

This means: Average faces are attractive, but not all of them. It is
crucial which faces are used to compute an average face. Composites made
from unattractive faces remain rather unattractive and average faces from
attractive faces remain attractive. This clearly contradicts the averageness
hypothesis, which holds that merely the number of faces contained in a
composite alone accounts for the attractiveness ratings.

Surprisingly, especially male faces benefit from being blended together
with respect to their attractiveness. This does not support older findings
that found positive effects only for women. Bad image quality of the faces,
especially blurred contours, may be the cause for it.

Why are the resulting average faces generally beautiful? One reason
might be the fact that by calculating average proportions unpleasant asymmetries
and irregularities become levelled out. Moreover, by blending together
several faces wrinkles and pimples gradually disappear. As a consequence,
the skin looks younger and perfectly smooth.

By conducting another experiment we could show that it is these skin-smoothing
side effects rather than the averaged proportions that account for the
increased attractiveness ratings of the composites (see reformed
facial proportions).